The system has stringent requirements for performance, scalability, and availability. The failure of any system element could potentially impact the level of capability in these areas. In order to prevent system crashes or predict when new capacity is needed, you must have some current and historical data on system usage.

The web servers, application servers, and database servers (both hardware and software) all play vital roles in the system. If one of the web servers fails, the load on the other web servers increases. This could lead to poor performance for the users or even to the failure of one of the remaining web servers. This sequence of events may well go unnoticed unless you can determine the health and capacity of the web servers.